Firing mechanism for mortars



April 11, 1950 s. WEISS FIRING MECHANISM FOR MORTARS 2 Sheets-Sheet 2 Filed Nov. 30, 1945 F1. Wm MIN? UNITED. STATE-S PATENT FIRING lHECHANKSM FOR MORTARS Saul Weiss, Washington, D. (1., assignor to the United States of America as represented by the Secretary of War Application November 30, 1945, Serial No. 632,100

17 Claims. (01. 8927) (Granted under the act of March 3, 1883, as

OFFICE amended April 30, 1928; 370 0. G. 757) The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

The invention relates to improvements in the firing mechanisms of mortars.

An important object ofthe invention is to permit the firingof a mortar in directional or low level fire. A mortar shell is ordinarily fired'by Figure 3 is a longitudinal section on the line dropping the complete round down the barrel or 3-3 of Figure 2,

tube of the mortar. A striker nut in the shell hits Figure 4 is a transverse section on the line 44 the top of the firing pin in the base of the barrel of Figure 3,

and is driven into the primer in the ignition car- Figure 5 is a transverse section on the line 55 tridge, firing thecartridge which then ignites the of Figure 3,

propelling charge within the shell, and the shell Figure 6 is a transverse section on the line 6-6 or projectile is expelled from the mortar by the of Figure 3,

pressure of the gases from the burning propellant. Figure 7 is a transverse section on the line 7-1 I-Ieretofore, a mortar has been restricted in firing of Figure 3,

upon targets where theelevation of the mortar Figure 8 is an elevation of the precocked spring tube was less than 40 degrees because'the shell for returning the lever arm after firing, showing would not gain sufficient momentum during its the spring housing sleeve in section,

drop within the tube or barrel of the mortar to Figure 9 is an end view of the same,

driv th fir D into the'primer 0f t e shell. Figure 10 is a longitudinal fragmentary section This invention provides means for instant switch of the firing pin bushing showing the firing pin ing f m dr p fi e to a lev Co d fi a in position for drop firing and illustrating the Will p i the mortal being fir at as W an construction for sealing against gases, and a e a is de i 1 do this y use Of a Selector Figure 11 is a section through the sear selector sear, as will be hereinafter pointed out and de and plunger taken on line ll-ll of Figure 2. scribed. The numeral i5 designates the base portion of Another important Object of the invention is a 60 mm. mortar into which the tube or barrel the arrange ent of h fi gp Within the 1111" H5 is fitted. It contains a rear portion or body pr v d mech ni so at the spring needed forterminating in a ball shaped end l8 to permit its activation is self-sealing against the corrosive tt t t a base plate or mount t Shown) and destructive effects of the expelling gases of and a forward tubular portion or cap [9 arranged the burning propellant, as well during lever opert engage t t 5 by means of Screw threads ation of the mortar as when the firing pin is ex- 25 within its forward owning The body tended into the tube for drop firing. Such sealm n n has been bored and counterbored t s ethods have not been needed in mortars vide a bore 2| of varying diameters and is proim d t p fi' S n the firing D use vided with a plurality of recesses to accommo- SllCh d p fi is fi Within a made a O date diiierent elements or units of the invention the base. as will hereinafter be pointed out.

Since a mortar iS a mobil we p n q The numeral 22 designates a bushing havinga frequent moving during enga t With a mushroom shaped head 23 which acts as an e y, Special 150018 for assembly and disasadapter or connector, connecting the body I! sembl of the parts should not be required. AS 45. and the cap is by means of screw threads 24 in its will be hereinafter pointed out, the mechanism of outer urface engaging screw threads i the this invention is self-contained and requires no largest diameter portion of the bore 2| and the p cia t s f a y sort t completely d q y screw threaded end of the cap I9. It is provided disassemble and reassemble the entire mechawith a screw-threaded recess 25 in the mushroom nisni under any conditions of use. shaped head 23 and a longitudinal bore 26 in its Additional objects, advantages and features of opposite end, said recess 25 and bore 25 being invention reside in the construction, arrangeconnected by a smaller bore 21, thus forming the ment and combination of parts involved in the shoulders 28 and 29 within the bushing 22. embodiment of the invention, as will be under- Arranged within the longitudinal bore 26 is a stood from t llowing description and arc-'55 helical compression spring 3B positioned around acompanying drawings, forming part of the specification, wherein similar numbers are used to designate like parts throughout the specification and drawings,

In these drawings:

Figure 1 is an elevation of the invention as applied to the tube of a mm. mortar,

Figure 2 is a plan view of the same,

striker 3|, one end of said spring being seated against an annular shoulder formed by a sleeve 32 on the end of the striker 3|. The other end of the said spring seats against a shoulder formed in the bore 2|. The sleeve 32 is arranged to move against the bias of the spring 3|] forward and backwards with the striker 3| within the bore 26, steadying the striker.

The striker 3| operates slidably within the bore 2| during activation. It is provided with a longitudinal groove 34 in its upper surface and a recess 35 in continuation of said groove to receive a pawl 36, the pawl being connected to the striker by a pivot pin 3! and so constructed and arranged that it may pivot counterclockwise as seen in Figure 3, against the force of a spring-pressed plunger 38 fixed in the body of the striker 3| in response to pressure against its curved upper surface but is limited in its clockwise pivotal movement by a shoulder 39 formed by the recess 35 in the body of the striker.

An operating lever 40 comprising a handle 4| formed integrally with a shaft 42 is revolvable in a recess 44 provided in the base portion H and is equipped with a flange 43. The shaft 42 has a tripper 46 fixed thereon within the base portion IT. The tripper 46 is generally circular in shape but has a protruding finger 41 to engage and operate the pawl 36 during lever operated firing of the mortar in a manner subsequently explained. The end of the shaft 42 is provided with a transverse slot (not shown) to engage the end of a precocked helical spring 46 coiled within a sleeve 49 (see Fig. 8) and having its other end engaged in a slot 50 in the base portion l1, said spring being positioned around the shaft 42 so that it will be further tensioned by rotation of the shaft and serve to return the operating lever 40 to its normal position after firing.

The numeral designates the selector sear embossed on its fiat outer face to indicate its adjustment and comprising a knob or head 52 knurled to facilitate manual rotation of a shaft 53 to which it is attached permanently by welding or otherwise, said shaft 53 being fixed in a recess 54 provided in the base portion H. The shaft 53 is arranged with a recess 55 near its end farthest removed from the knob 52 engaging the striker 3| loosely within the said recess 55 at a point near the end of the said striker when the striker is in normal position in such manner that the striker 3| may pass freely through the said recess 55 without interference during lever operation of the mortar, but so positioned that when the shaft 53 is rotated by the manual turning of the knob 52, the striker 3| is forced forward by the pressure of the bottom of the recess 55 against the end of the striker 3|, thus forcing the striker 3| forwardly and projecting firing pin 65 into position for drop fire.

The under side of knob 52 is provided with a pair of circumferentially-spaced arcuate notches 82, as clearly shown at Figure 11. A locking plunger 56 has a head 58 adapted to smoothly fit a respective notch when the knob is in its lever fire and drop fire positions, The plunger is mounted within a bore 5'! in portion IT, for sliding in a direction parallel with shaft 53 and is urged into outward position locking shaft 53, by a spring 59 in a manner obvious from inspection of Figure 5. Thus, when knob is in either its lever fire position or its drop fire position, a portion of head 58 seats in a respective one of notches 82 and locks the knob 52 and its shaft 53, against rotation. Since a portion of head 58 is exposed, it may be manually forced inwardly against the thrust of spring 59 to release knob 52 and permit turning thereof. A cover plate 60 is pivoted on a pin 6| extending through a bore in portion |1 parallel with shaft 53, as will be clear from inspection of Figure 6. Plate 60 has a fiat top to extend over and close the slot in which tripper 46 operates as shown at Figure 4 and downwardly-turned sides to fit snugly over and about the top of portion See Figures 3 to 6. One of the downwardly-turned sides is slotted to fit smoothly about shaft 42 to thereby cooperate with flange 43 to hold the shaft against axial outward movement as shown at Figure 4. The other downwardly-turned side has a hole through which the head 53 of plunger 56 extends. This hole, as shown in Figure 5, cooperates with a peripheral shoulder between head 58 and the body of plunger 56, to prevent outward axial movement of the plunger when shaft 53 and its knob'5l are removed.

The set screw 62 in the side of base portion I1 is arranged for screw thread engagement, as shown in Figure 1, within the base portion and serves to lock the entire mechanism in place by engagement in an annular groove 18 in the body of the adaptor 22.

The bushing or plug 63 arranged for screw engagement within the recess 25 is bored and counter bored to provide a bore 64 of varying diameters to accommodate a firing pin 65 of a shape substantially as shown in Figures 3 and 10.

Plug 63 is hexagonal with the distance across its flats a little less than the distance between the opposed walls of a slot or channel 6! formed in base l5. Thus, when base |5 and barrel l5 are removed, base I5 may be used as a wrench to remove plug 63 from adaptor 22 by placing channel 61 over the plug 63. An undercut recess 68 conforming to the shape of the forward portion of the firing pin 65 provides sealing means against the propelling gases within the tube US during drop fire by engaging an annular projection 8|] formed by an oppositely opposed undercut on the said firing pin, as may be seen in Figure 10, and an annular recess 69 is provided in the base of the said bushing 63 to coact with a coincidental shallow recess in head 23 thereby forming a chamber to house a grooved washer 10 serving as a sealing means against the said gases during lever fire. A compressible coil spring II is disposed around the rear portion 14 of the firing pin 65 between the washer T0 and a sliding lock washer 13 of the same outside diameter as the bore 21. The lock washer 13 also serves as a guide for the firing pin during its passage through the said bore. The lock washer is provided with a recess 75 to permit its removal through an annular groove 12 when forced into the bore 21 against the restraint of the spring H which normally holds it in place against an annular shoulder 16 formed by the base 11 of the firing pin 65.

In lever fire the various parts of the mechanism are positioned as shown in Figure 3. The trip- Per 46 is rotated by the shaft 42 actuated by the lever 40. The finger 41 of the rotating tripper 46 engages the forward end of the pawl 36 forcing the said pawl, and striker 3| to which it is attached by the pivot pin 31, rearward within the bore 2| against the resistance of the spring 36, compressing the said spring by the pressure of the sleeve 32 attached to the striker 3|. The spring 30 is released from this restraint by the action of the revolving tripper finger 41 passing over the pawl 36 and the released energy drives the striker 3| and the sleeve 32 forward against the firing pin 65, forcing'said firing pin through the opening 19 and against the round in the tube H5, at the same time compressing the spring 1!. When the forward movement of the firing pin 65 has ceased, it is returned. to its normal position by the relaxing spring ll, said spring being protected from the expelling gases of the burning propellant during fire by the sealing action of the grooved Washer 70. In the meantime, the energy of the precocked spring 48 disposed around the lever shaft 42 has returned the lever to its original position when the pawl 36 is depressed by the camming action of the finger 4'! against its curved upper surface, moving it out of the plane of the revolving tripper 46.

Conversion of the mechanism to drop fire is effected by pressing the plunger 56 into the recess 51 against the pressure of the spring 59, releasing the head 52 of the selector sear 5! which is now turned 90 degrees in a clockwise direction, as seen at Figure 3, until the embossing indicating drop fire is above the said plunger 55. Release of the plunger will cause the selector sear 5| to lock in this position, as heretofore described, and the mortar is ready for use in drop fire. When the selector sear 5| was turned, the end of striker 3| was engaged by the inner surface of recess 55 forcing it forward against the resistance of the spring 30, blocking any further forward or backward movement of the said striker and locking the lever 40 by the pressure of pawl 36 against tripper finger 41. The forward action of striker 3| forces the firing pin 65 through the opening 19 after compression of the firing pin spring H, and the said firing pin is held fixed for use in drop fire by the resistance of the striker 3|. Gas is prevented from entering by the sealing action of the projection 80 in the undercut recess 88 formed in bushing 63.

In changing back to lever fire, plunger 56 is operated as heretofore described, and the selection sear 51 is turned 90 degrees in a counterclockwise direction until the embossin indicating lever fire is above the said plunger 56, as may be observed in Figure 1, where it is locked by the release of the said plunger 55. This turning action has released the striker 3| from engagement within the recess 55 and the said striker is forced back to its original position by the energy of the sprin 30, releasing the tripper finger 41 from the restraint of pawl 36 and leaving the lever 40 ready for action. The relaxing of the compressed spring II when the firing pin 65 is freed of the pressure of the striker 3| forces return of the firing pin to its original position as shown clearly in Figure 3.

As heretofore mentioned, an important feature of the invention is the ease with which it may be disassembled without use of any specialtools or equipment. The base portion I! may be disengaged from cap portion 19, and cap portion 19 may be disengaged from mortar tube 1 6 manually after the set screw 62 has been removed or loosened. Lifting of the cover plate-5t permits removal of the tripper 46 and the lever arm 42. The adapter 22 is provided with slots (not shown) in which the edge of the base plate of the mortar may be inserted to act as a lever arm in disengaging the adapter 22 from the cap I 9, and as already pointed out, the bushing 63 may be disengaged from the mushroom head 23 in order to remove the firing pin 65, grooved washer 10, and the spring H by employing recess 61 provided in base portion I! as a wrench for the hexagonal face 66.

I have disclosed the invention in the best construction known to me, but it will nevertheless be understood that this is purely exemplary, and that changes and modifications in the construction, arrangement and combination of parts otherwise than as specifically claimed, and substitution of materials and equipment, mechanical or otherwise, may be made without departing from the spirit of the invention set forth in the appended claims. 1

Having thus described the invention, I claim:

1. A selector sear adjustable from the exterior for changing the mode of fire of a mortar comprising a manually rotatable head suitably embossed on its outer face to indicate its adjustment, a shaft connected to said head and constructed and arranged to rotate with it, a striker element arranged to move forward and rearward within the firing mechanism of a mortar at right angles to said shaft, a recess in said shaft so positioned that it will engage the striker element of the mortar to permit by rotation of said sear a selective choice of either a reciprocating movement of the striker element through the recess or complete blocking of said reciprocating movement, a pawl pivoted in said striker element, lever operated means for engaging said pawl to retract and then release said striker element for firing movement, and a firing pin arranged to be activated by said striker element during firing movement of said element, said pawl permitting said lever operated means to, move into striker-retracting position when released.

2. A firing pin provided with an extended nose portion, a shoulder having an annular undercut about its upper surface and a cylindrical stem portion, a bushing having a plurality'of coaxial bores adapted to slidably engage the said firing pin, said bushing having an annular undercut oppositely opposed to the undercut on the shoulder of the firing pin and an annular recess in its rearward face, a grooved washer set in the rearward recess of the bushing and positioned around the stem portion of the firing pin, a lock Washer connected to the end of the firing pin stem and arranged to move with it and an actuating coil spring disposed around said firing pin stem, held between the grooved Washer and the lock Washer, for returning the firing pin when released from pressure.

3. In a firing mechanism for a mortar adapted for selective lever on drop fire, said mortar having a tubular body arranged to be mounted on a base and launching tube carried by said base, a tubular bushing threadedly mounted in said body, an enlarged head on said bushing constructed and arranged to be positioned in said launching tube, a spring-urged striker reciprocably mounted in said bushing, a firing pin carried in said head and movable therethrough, said firing pin having a portion thereof projecting into said bushing in the path of said striker, sealing means in said head to restrict passage of gasses of combustion from said launching tube to said bushing, lever means for actuating said striker, and a rotatable sear carried by said body constructed and arranged to be positioned in the path of saidstriker to prevent the reciprocal movement thereof thereby arranging the said mechanism for drop fire.

4. The structure of claim 3 wherein the lever means for actuating the said striker includes a rotatable lever shaft, a tripper mounted thereon and arranged to rotate therewith, and a pawl pivotably mounted on said striker and adapted to be wiped by said tripper.

5. The structure of claim 4 in which the rotatable sear is provided with a longitudinal cut-out portion providing a recess through which the striker reciprocates freely while said sear is maintained in a first position for lever fire, the bottom surface of said recess being arranged to engage the adjacent-end of said striker to move said striker forward in said bushing so that a portion of said firing pin will be projected forward and into the launching tube and reciprocation of the said striker will be prevented when said sear is rotated and maintained in a second position for drop fire. '1

6. The structure of claim 5 in which a manually operated spring-urged plunger operable from outside said mortar, is mounted in said body and constructed and arranged to restrict rotation of said sear.

'7. The structure of claim 6 in which the enlarged head is arranged with a threaded plug, the said plug being bored and counter-bored to provide a housing for a portion of said firing pin and provide an annular chamber adjacent thereto in which said gas sealing means is positioned.

8. The structure of claim '7 in which the sealing means positioned in said annular chamber comprises a grooved washer having a central opening to allow passage therethrough of the firing pin, the said washer being restrained from moving from said chamber by pressure of a portion of said plug thereon.

9. The structure of claim 3 in which resilient means are carried in said head to return said firing pin to a position in the path of said striker after it has been projected forward into said launching tube.

10. The structure of claim 9 in which a precocked helical spring coiled within a sleeve is carried on said lever shaft and engaged thereon in a manner which will further tension said spring when said shaft is rotated, to return the said lever shaft to its normal position.

11. The structure of claim 10 in which a cover member is pivotably mounted on said body, the said member being arranged to removably engage and retain said lever means in said body, and protect said firing mechanism in said body against the entry of dirt and foreign objects.

12. In a firing mechanism for a mortar having barrel cap means closing the breech end thereof, a firing pin reciprocably mounted in said cap means, a striker reciprocable in said cap means rearwardly of said firing pin and operable to move said pin axially from a first retracted position to a second firing position, a spring-pressed latch carried by said striker, spring means urging said striker toward said firing pin, and first manually operable means carried by said barrel cap means to engage said latch, move said striker against the force of said spring means and then release said latch, all in one direction of movement of said manually operable means.

13. A firing mechanism as recited in claim 12, and second manually operable means on said cap means to engage and positively move said striker to project and hold said pin in firing position.

1.4. In a firing mechanism for a mortar having a barrel and cap means rigidly secured to said barrel to close the breech end. thereof, a firing pin reciprocable in a central aperture in said cap means from a first retracted position to a second firing position, a first spring urging said pin into first position, a striker reciprocable in said cap means to engage said firing pin and move the same from first to second position against the urge of said first spring, a second spring urging said striker toward said firing pin, a pawl pivoted on said striker, a tripper pivoted in said cap means and manually rotatable in one direction to engage said pawl to move said striker away from said firing pin and then release said pawl to the action of said second spring, and means carried by said striker yieldingly urging said pawl into tripper-engaging position.

15. A firing mechanism as recited in claim 14, and manually-operable means on said cap means to positively move and hold said striker, and firing pin into forward firing position.

16. A firing mechanism as recited in claim 14, and manually-operable means to positively move and hold said striker and firing pin into firing position, said means comprising a shaft journaled in said cap means and having a semicylindrical portion cut away to form a passageway for said striker in one position of said shaft, said shaft being rotatable into a second position to cam said striker forwardly, and means releasably locking said shaft in selected position.

17. In a mortar firing mechanism, a bushing having central bores opening through its forward and rear faces, respectively, and connected by a central hole of less diameter than said bores, a plug fixed in said forward bore and having a central aperture, a firing pin reciprocably mounted in said hole and having a piston-like flange fitting said forward bore and a reduced nose fitting the aperture in said plug, an obturating washer fitting about the cylindrical body portion of said firing pin rearwardly of said flange, said washer being clamped by and be tween said bushing and plug, said firing pin being reciprocable from a first firing position in which its nose projects exteriorly from said plug, to a second position in which said nose is retracted within said plug and its body portion projects into the rearward bore in said bushing, an abutment carried by the rear end of said body portion and a coil spring surrounding said portion and reacting between said washer and abutment to urge said firing pin into retracted position.

SAUL WEISS.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,399,243 Bergman Dec. 6, 1921 1,859,590 Koppel May 24, 1932 FOREIGN PATENTS Number Country Date 168,396 Great Britain Aug. 21, 1921 570,613 France Jan. 18, 1924 760,542 France Dec. 14, 1933 832,483 France July 4, 1938 

